The hippocampal formation of the rat brain has been implicated in guiding movement through space and in orienting or attending to cues. It is argued that each behavioral state is associated with a different frequency band of rhythmic slow activity (RSA) recorded electrically from the hippocampus: fast RSA (7-11 Hz) accompanies spatial activities and slow RSA (4-7 Hz) accompanies attentive behaviors. Pharmacological and anatomical evidence for the separation of slow and fast RSA are reviewed and found to be consistent with neurobehavioral data in suggesting that fast RSA is driven primarily by inputs from the septal region and slow RSA from the entorhinal cortex. The aim of the proposed work is to attempt to separate inputs of slow and fast RSA. An initial set of experiments on rats anesthetized with urethane will refine preliminary observations that RSA can be driven by electrical stimulation of the perforant path (from the entorhinal cortex). Techniques used will include laminar analysis of the generator in the hippocampus, systematic variation of stimulation frequency to determine if a lowest-threshold stimulation rate exists, and administration of atropine and eserine to disrupt and enhance, respectively, the elicited RSAs. A second set of experiments will compare the effects of systematic manipulations of septal and entorhinal inputs in waking rats to examine generator sites, types of evoked behaviors, intensity thresholds as a function of frequency, and the effects of cholinergic and other drugs. The data from these approaches should converge to establish the degree of separability of the systems for driving fast and slow RSA.